Combined process for alkylation of light olefins using ionic liquid catalysts

Abstract

Processes for the direct alkylation of ethylene with isobutane or isopentane using a highly active ionic liquid alkylation catalyst are described. Ethylene is sent to a high-temperature alkylation reactor loop, and C 3 , C 4 , and C 5 olefins are routed to a low temperature alkylation reactor loop. In each reactor, the olefins are contacted with an excess of isobutane or isopentane in the presence of a highly active ionic liquid catalyst. Portions of the reactor effluent streams are fed to a common downstream catalyst separation and product fractionation sections. The remainder of the reactor effluent is recycled back to the respective alkylation reactor.

What is claimed is: 
     
       1. An integrated process for ionic liquid alkylation of C 2  to C 5  olefins comprising:
 reacting an ethylene feed stream comprising ethylene and an isoparaffin feed stream comprising isobutane in the presence of an ionic liquid catalyst comprising an ionic liquid in a high-temperature alkylation reactor under first alkylation reaction conditions to form a first alkylation effluent stream comprising ionic liquid, isobutane, and alkylate, wherein the first alkylation reaction conditions comprise a temperature in a range of 30° C. to 100° C. and a pressure in a range of 100 psig to 1000 psig; 
 reacting a C 3 -C 5  olefin feed stream comprising olefins having 3 to 5 carbon atoms and a second isoparaffin feed stream comprising isobutane in the presence of a second ionic liquid catalyst comprising ionic liquid in a low temperature alkylation reactor under second alkylation reaction conditions to form a second alkylation effluent stream comprising ionic liquid, isobutane, and alkylate, wherein the second alkylation reaction conditions comprise a temperature in a range of 0° C. to 35° C. and a pressure in a range of 40 psig to 300 psig; 
 combining a first portion of the first alkylation effluent stream and a first portion of the second alkylation effluent streams to form a combined stream; 
 separating the combined stream into an ionic liquid recycle stream comprising ionic liquid and a hydrocarbon stream comprising isobutane and alkylate; 
 separating the hydrocarbon stream into an isoparaffin recycle stream comprising isobutane and an alkylate stream comprising alkylate; and 
 recovering the alkylate stream. 
 
     
     
       2. The process of  claim 1  further comprising:
 dividing the first alkylation effluent stream into the first portion and a second portion; 
 heating the second portion of the first alkylation effluent stream and recycling the heated second portion of the first alkylation effluent stream to the high temperature alkylation reactor; 
 dividing the second alkylation effluent stream into the first portion and a second portion; and 
 cooling the second portion of the second alkylation effluent stream and recycling the cooled second portion of the second alkylation effluent stream to the low temperature alkylation reactor. 
 
     
     
       3. The process of  claim 1  further comprising:
 recycling the isoparaffin recycle stream to the high temperature alkylation reactor, the low temperature reactor, or both. 
 
     
     
       4. The process of  claim 1  further comprising:
 recycling the ionic liquid recycle stream to the high temperature alkylation reactor, the low temperature reactor, or both. 
 
     
     
       5. The process of  claim 1  further comprising:
 regenerating a portion of the ionic liquid recycle stream to form a regenerated ionic liquid stream; and 
 recycling the regenerated ionic liquid stream to the high temperature alkylation reactor, the low temperature reactor, or both. 
 
     
     
       6. The process of  claim 1  further comprising:
 treating an ethylene stream to remove contaminants to form a treated ethylene stream, wherein the treated ethylene stream comprises the ethylene feed stream; and 
 treating a C 3 -C 5  olefin stream comprising olefins having 3 to 5 carbon atoms to remove contaminants to form a treated C 3 -C 5  olefin stream, wherein the treated C 3 -C 5  olefin stream comprises the C 3 -C 5  olefin feed stream. 
 
     
     
       7. The process of  claim 1 , wherein the first alkylation reaction conditions comprise an overall paraffin to ethylene molar ratio of 2:1 to 20:1, and a residence time in a range of 5 minutes to 1 hr. 
     
     
       8. The process of  claim 1 , wherein the second alkylation reaction conditions comprise an overall paraffin to olefin molar ratio of 2:1 to 20:1, and a residence time in a range of 1 minute to 1 hr. 
     
     
       9. The process of  claim 1  wherein the ionic liquid comprises an organic cation and a halometallate anion and wherein the organic cation comprises an ammonium cation, a pyrrolidinium cation, a pyridinium cation, an imidazolium, a phosphonium cation, or a combination thereof. 
     
     
       10. The process of  claim 1 , wherein the ionic liquid comprises an organic cation and a halometallate anion and wherein the halometallate anion comprises a metal selected from Al, Ga, In, Mn, Fe, Co, Ni, Cu, Zn, or a combination thereof, and a halide selected from F, Cl, Br, I, or a combination thereof. 
     
     
       11. The process of  claim 1  wherein one or more of:
 the ionic liquid is present in an amount of from 5 vol % to 60 vol % of a total volume of material in the high temperature alkylation reactor; 
 the ionic liquid is present in an amount of from 1 vol % to 10 vol % of a total volume of material in the low temperature alkylation; and 
 the ionic liquid is present in an amount of from 1 vol % to 60 vol % of a total volume of material in the combined stream. 
 
     
     
       12. The process of  claim 1  wherein the alkylate in the alkylate stream has a research octane number (RON) of 90 or more. 
     
     
       13. An integrated process for ionic liquid alkylation of C 2  to C 5  olefins comprising:
 reacting an ethylene feed stream comprising ethylene and an isoparaffin feed stream comprising isobutane with an ionic liquid catalyst comprising an ionic liquid in a high temperature alkylation reactor under first alkylation reaction conditions to form a first alkylation effluent stream comprising the first ionic liquid, the isoparaffin, and alkylate, wherein the first alkylation reaction conditions comprise a temperature in a range of 30° C. to 100° C., a pressure in a range of 100 psig to 1000 psig, an overall paraffin to ethylene molar ratio of 2:1 to 20:1, and a residence time in a range of 5 minutes to 1 hr; 
 reacting a C 3 -C 5  olefin feed stream comprising olefins having 3 to 5 carbon atoms and a second isoparaffin feed stream comprising isobutane with the ionic liquid catalyst in a low temperature alkylation reactor under second alkylation reaction conditions to form a second alkylation effluent stream comprising the second ionic liquid, the isoparaffin, and alkylate, wherein the second alkylation reaction conditions comprise a temperature in a range of 0° C. to 35° C., comprise a pressure in a range of 40 psig to 300 psig, an overall paraffin to olefin molar ratio of 2:1 to 20:1, and a residence time in a range of 1 minute to 1 hr; 
 dividing the first alkylation effluent stream into a first portion and a second portion; 
 heating the second portion of the first alkylation effluent stream and recycling the heated second portion of the first alkylation effluent stream to the high temperature alkylation reactor; 
 dividing the second alkylation effluent stream into a first portion and a second portion; 
 cooling the second portion of the second alkylation effluent stream and recycling the cooled second portion of the second alkylation effluent stream to the low temperature alkylation reactor; 
 combining the first portion of the first alkylation effluent stream and the first portion of the second alkylation effluent streams to form a combined stream; 
 separating the combined stream into an ionic liquid recycle stream comprising the ionic liquid and a hydrocarbon stream comprising the isoparaffin and the alkylate; 
 separating the hydrocarbon stream into an isoparaffin recycle stream comprising the isoparaffin and an alkylate stream comprising the alkylate; 
 recycling the isoparaffin recycle stream to the high temperature alkylation reactor, the low temperature reactor, or both; 
 recycling the ionic liquid recycle stream to the high temperature alkylation reactor, the low temperature reactor, or both; and 
 recovering the alkylate stream. 
 
     
     
       14. The process of  claim 13  further comprising:
 regenerating a portion of the ionic liquid recycle stream to form a regenerated ionic liquid stream; and 
 recycling the regenerated ionic liquid stream to the high temperature alkylation reactor, the low temperature reactor, or both. 
 
     
     
       15. The process of  claim 13  further comprising:
 treating an ethylene stream to remove contaminants to form a treated ethylene stream, wherein the treated ethylene stream comprises the ethylene feed stream; 
 treating a C 3 -C 5  olefin stream comprising olefins having 3 to 5 carbon atoms to remove contaminants to form a treated C 3 -C 5  olefin stream, wherein the treated C 3 -C 5  olefin stream comprises the C 3 -C 5  olefin feed stream. 
 
     
     
       16. The process of  claim 13  wherein the ionic liquid comprises an organic cation and a halometallate anion and wherein the organic cation comprises an ammonium cation, a pyrrolidinium cation, a pyridinium cation, an imidazolium, a phosphonium cation, or a combination thereof. 
     
     
       17. The process of  claim 13  wherein the ionic liquid comprises an organic cation and a halometallate anion and wherein the halometallate anion comprises a metal selected from Al, Ga, In, Mn, Fe, Co, Ni, Cu, Zn, or a combination thereof, and a halide selected from F, Cl, Br, I, or a combination thereof. 
     
     
       18. The process of  claim 13  wherein one or more of:
 the ionic liquid is present in an amount of from 5 vol % to 60 vol % of a total volume of material in the high temperature alkylation reactor; 
 the ionic liquid is present in an amount of from 1 vol % to 10 vol % of a total volume of material in the low temperature alkylation; and 
 the ionic liquid is present in an amount of from 1 vol % to 60 vol % of a total volume of material in the combined stream. 
 
     
     
       19. The process of  claim 13  wherein the alkylate in the alkylate stream has a research octane number (RON) of 90 or more.